Experimental and Numerical Investigation of a Hydrogen Combustion Chamber Under Various Inlet Conditions

2014 ◽  
Author(s):  
Heidemarie Malli ◽  
Kurt Eckerstorfer ◽  
Oliver Borm ◽  
Peter Leitl
Keyword(s):  
Combustion Chamber ◽  
Development Stage ◽  
Combustion Regime ◽  
Hydrogen Combustion ◽  
Emission Characteristics ◽  
Low Oxygen ◽  
Combustion Chambers ◽  
Mild Combustion ◽  
Combustion Technology ◽  
Inlet Conditions

Flameless combustion, MILD (moderate or intense low oxygen dilution) combustion and HiTAC (high temperature air combustion) all refer to a combustion regime characterized by high temperatures and a high dilution of reactants. In most cases, this is achieved by recirculating exhaust gases. This leads to comparatively low oxygen concentrations, a largely uniform temperature field and to a drastically reduced NOx formation. Up to now, the application of this combustion technology for gas turbine combustion chambers is still in an early development stage. Most investigations of flameless or MILD combustion chambers have been carried out for methane or certain fuel blends. Since this combustion technology has already successfully demonstrated low NOx emissions without the need of premixing with its potential risks of flashback and autoignition, it might be a promising technology for hydrogen burning combustion chambers. The scope of this paper is to investigate a hydrogen combustion chamber for its NOx emission characteristics and for its use in the flameless or MILD combustion regime. Thus, the influence of different inlet parameters (excess air ratio, thermal input of hydrogen, inlet velocity of the combustion air, pressure inside the combustion chamber) on the emission characteristics of the combustion chamber are examined experimentally. Additionally, for one operating point, a two–dimensional numerical simulation of the combustion chamber was carried out.

Actuation Studies for Active Control of Mild Combustion for Gas Turbine Application

2014 ◽  
Author(s):  
Emilien Varea ◽  
Stephan Kruse ◽  
Heinz Pitsch ◽  
Thivaharan Albin ◽  
Dirk Abel
Keyword(s):  
Combustion Chamber ◽  
Gas Turbine ◽  
Active Control ◽  
Gas Turbines ◽  
Reverse Flow ◽  
Air Flow ◽  
Combustion Regime ◽  
Nox Emissions ◽  
Low Oxygen ◽  
Mild Combustion

MILD combustion (Moderate or Intense Low Oxygen Dilution) is a well known technique that can substantially reduce high temperature regions in burners and thereby reduce thermal NOx emissions. This technology has been successfully applied to conventional furnace systems and seems to be an auspicious concept for reducing NOx and CO emissions in stationary gas turbines. To achieve a flameless combustion regime, fast mixing of recirculated burnt gases with fresh air and fuel in the combustion chamber is needed. In the present study, the combustor concept is based on the reverse flow configuration with two concentrically arranged nozzles for fuel and air injections. The present work deals with the active control of MILD combustion for gas turbine applications. For this purpose, a new concept of air flow rate pulsation is introduced. The pulsating unit offers the possibility to vary the inlet pressure conditions with a high degree of freedom: amplitude, frequency and waveform. The influence of air flow pulsation on MILD combustion is analyzed in terms of NOx and CO emissions. Results under atmospheric pressure show a drastic decrease of NOx emissions, up to 55%, when the pulsating unit is active. CO emissions are maintained at a very low level so that flame extinction is not observed. To get more insights into the effects of pulsation on combustion characteristics, velocity fields in cold flow conditions are investigated. Results show a large radial transfer of flow when pulsation is activated, hence enhancing the mixing process. The flame behavior is analyzed by using OH* chemiluminescence. Images show a larger distributed reaction region over the combustion chamber for pulsation conditions, confirming the hypothesis of a better mixing between fresh and burnt gases.

scholarly journals Numerical study of flame structure in the mild combustion regime

2015 ◽  
Vol 19 (1) ◽  
pp. 21-34 ◽  
Author(s):  
Amir Mardani ◽  
Sadegh Tabejamaat
Keyword(s):  
Fuel Injection ◽  
Numerical Study ◽  
Flame Structure ◽  
Combustion Regime ◽  
Low Oxygen ◽  
Mixing Rate ◽  
Jet Flame ◽  
Reduced Mechanism ◽  
Mild Combustion ◽  
O2 Concentration

In this paper, turbulent non-premixed CH4+H2 jet flame issuing into a hot and diluted co-flow air is studied numerically. This flame is under condition of the moderate or intense low-oxygen dilution (MILD) combustion regime and related to published experimental data. The modelling is carried out using the EDC model to describe turbulence-chemistry interaction. The DRM-22 reduced mechanism and the GRI2.11 full mechanism are used to represent the chemical reactions of H2/methane jet flame. The flame structure for various O2 levels and jet Reynolds numbers are investigated. The results show that the flame entrainment increases by a decrease in O2 concentration at air side or jet Reynolds number. Local extinction is seen in the upstream and close to the fuel injection nozzle at the shear layer. It leads to the higher flame entertainment in MILD regime. The turbulence kinetic energy decay at centre line of jet decreases by an increase in O2 concentration at hot Co-flow. Also, increase in jet Reynolds or O2 level increases the mixing rate and rate of reactions.

Simulation Research on Matching of Spray and Combustion Chamber Geometry in Diesel Engine

2011 ◽  
Vol 199-200 ◽  
pp. 193-197 ◽  
Author(s):  
Cheng Cheng Zhang ◽  
Qian Wang ◽  
Zhi Xia He ◽  
Ping Jiang
Keyword(s):  
Temperature Field ◽  
Diesel Engine ◽  
Combustion Chamber ◽  
Shape Change ◽  
Emission Characteristics ◽  
Mixed Gas ◽  
Combustion Chambers ◽  
Simulation Research ◽  
Different Types ◽  
Combustion Processes

In order to investigate the influence of combustion chamber geometry on spray and combustion characteristics in diesel engine, universal CFD software STAR-CD is applied to simulate the combustion processes in three different types of combustion chambers of diesel engine. The effect of combustion chamber geometry on in–cylinder air motion, temperature field and exhaust emissions are researched in this paper. Comparing with experimental results, calculation models are proved to be validity. The results show that differences of combustion chamber shape change the characteristic of flow field in cylinder, which affects the formation of mixed gas and determines the combustion and emission characteristics.

scholarly journals Experimental and Numerical Investigation of a MILD Combustion Chamber for Micro Gas Turbine Applications

Energies ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 3363 ◽  
Author(s):  
Valentina Fortunato ◽  
Andres Giraldo ◽  
Mehdi Rouabah ◽  
Rabia Nacereddine ◽  
Michel Delanaye ◽  
...  
Keyword(s):  
Combustion Chamber ◽  
Gas Turbine ◽  
Energy Production ◽  
Kinetic Mechanism ◽  
Combustion Model ◽  
Low Oxygen ◽  
Micro Gas Turbine ◽  
Air Inlet ◽  
Mild Combustion ◽  
Stirred Reactor

In the field of energy production, cogeneration systems based on micro gas turbine cyclesappear particularly suitable to reach the goals of improving efficiency and reducing pollutants.Moderate and Intense Low-Oxygen Dilution (MILD) combustion represents a promising technologyto increase efficiency and to further reduce the emissions of those systems. The present work aims atdescribing the behavior of a combustion chamber for a micro gas turbine operating in MILD regime.The performances of the combustion chamber are discussed for two cases: methane and biogascombustion. The combustor performed very well in terms of emissions, especially CO and NOx,for various air inlet temperatures and air-to-fuel ratios, proving the benefits of MILD combustion.The chamber proved to be fuel flexible, since both ignition and stable combustion could be achievedby also burning biogas. Finally, the numerical model used to design the combustor was validatedagainst the experimental data collected. The model performs quite well both for methane and biogas.In particular, for methane the Partially Stirred Reactor (PaSR) combustion model proved to be thebest choice to predict both minor species, such as CO, more accurately and cases with lower reactivitythat were not possible to model using the Eddy Dissipation Concept (EDC). For the biogas, the mostappropriate kinetic mechanism to properly model the behavior of the chamber was selected

On the Computer-Aided Conversion of a Diesel Engine to CNG-Dedicated or Dual Fuel Combustion Regime

2012 ◽  
Author(s):  
Teresa Donateo ◽  
Arturo de Risi ◽  
Domenico Laforgia
Keyword(s):  
Diesel Engine ◽  
Combustion Chamber ◽  
Cfd Simulation ◽  
Combustion Regime ◽  
Fuel Combustion ◽  
Dual Fuel ◽  
Combustion Chambers ◽  
Analytical Methodology ◽  
Design Alternatives ◽  
Dual Fuel Combustion

The paper proposes a cost-saving analytical methodology using empirical based models to efficiently evaluate design alternatives in the optimization of a CNG converted diesel engine. The procedure is performed in five steps. Firstly, a database of different combustion chambers that can be obtained from the original piston is obtained. The chambers in the database differ for the shape of the bowl, the value of the compression ratio, the offset of the bowl and the size of the squish region. The second step of the procedure is the selection, from the first database, of the combustion chambers able to resist to the mechanical stresses due to the pressure and temperature distribution at full load. For each combination of suitable combustion chamber shape and ignition timing, a CFD simulation is used to evaluate the combustion performance of the engine. Then, a post-processing procedure is used to evaluate the detonation tendency and intensity of each combination. All the tools developed for the application of the method have been linked in the ModeFrontier optimization environment in order to perform the final choice of the combustion chamber. The overall process requires not more of a week of computation on the 4 processor servers considered for the optimization. Moreover, the selected chambers can be obtained from the original piston of the engine. Therefore, the conversion cost of the engine is quite small compared with the case of a completely new piston. The procedure can be applied to diesel engines to be converted to either CNG dedicated or dual fuel combustion. The main aspects and challenges to be taken into account in both cases are also analyzed.

Effects of hydrogen addition on structure and NO formation of highly CO-Rich syngas counterflow nonpremixed flames under MILD combustion regime

2021 ◽  
Vol 46 (17) ◽  
pp. 10518-10534
Author(s):  
Namsu Kim ◽  
Yongmo Kim ◽  
Mohammad Nazri Mohd Jaafar ◽  
Muhammad Roslan Rahim ◽  
Mazlan Said
Keyword(s):  
Combustion Regime ◽  
Nonpremixed Flames ◽  
Hydrogen Addition ◽  
No Formation ◽  
Mild Combustion

scholarly journals Modeling of Spray Combustion with a Steady Laminar Flamelet Model in an Aeroengine Combustion Chamber Based on OpenFOAM

2018 ◽  
Vol 2018 ◽  
pp. 1-13
Author(s):  
Yinli Xiao ◽  
Zupeng Wang ◽  
Zhengxin Lai ◽  
Wenyan Song
Keyword(s):  
Combustion Chamber ◽  
High Performance ◽  
Numerical Models ◽  
Spray Combustion ◽  
Combustion Chambers ◽  
Flamelet Model ◽  
Steady Laminar ◽  
Good Agreement ◽  
Laminar Flamelet ◽  
Laminar Flamelet Model

The development of high-performance aeroengine combustion chambers strongly depends on the accuracy and reliability of efficient numerical models. In the present work, a reacting solver with a steady laminar flamelet model and spray model has been developed in OpenFOAM and the solver details are presented. The solver is firstly validated by Sandia/ETH-Zurich flames. Furthermore, it is used to simulate nonpremixed kerosene/air spray combustion in an aeroengine combustion chamber with the RANS method. A comparison with available experimental data shows good agreement and validates the capability of the new developed solver in OpenFOAM.

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